On Tue, 2012-07-17 at 06:18 +0200, Mike Galbraith wrote:

quoted

There's that too. But the issue I was talking about is with all trylock
loops. As holding an rt-mutex now disables migration, if a high priority
process preempts a task that holds the lock, and then the high prio task
starts spinning waiting for that lock to release, the lower priority
process will never get to run to release it. The cpu_chill() doesn't
help.

Hrm.  I better go make a testcase, this one definitely wants pounding
through thick skull.

Actually, I was mistaken. I forgot that we defined 'cpu_chill()' as
msleep(1) on RT, which would keep a deadlock from happening.

It doesn't explain the performance enhancement you get :-/

-- Steve